Photographic emulsions containing polymeric color formers



Sept. 16, 1958 L. M. MINSK EI'AL 2,352,331

PHOTOGRAPHIC EMULSIONS CONTAINING POLYMERIC COLOR -FORMERS Filed Oct. 1a, 1953 &@ 5 3 omwmc COLOR FORMER- LOU/5 M. MIA/SK F RE 0 C. DUE IVNE B/E R IN V EN TORS Maw ATTORNEY'E AGENT United States PHOTOGRAPHIC EMULSIONSCONTAINING' POLYIVIERIC. COLOR FORMERS Louis M. Minsk and Fred C. Duennebier, Rochester,

N. Y assignors to Eastman Kodak Company, Rochester, N. -Y., a corporation of New Jersey ApplicationOctober 13, 1953, Serial No. 385,726

11 Claims. (Cl. 96-97) facilitates their incorporation into photographic emulsions'. Sincesuchv prior polymeric'color formers possess alkali solubility; when they are incorporated into a hydrophilic organic colloid emulsion layers they depend for their nondiftusing characteristics upon the polymeric chain and hydrophobic radicals attached thereto.

The polymeric couplers of our invention are free of such alkalisolubilizing groups, yet are reactive toward color developers, and are characterized by very low difi'usion properties in photographic emulsion layers. However, the lack of alkali solubilizing groups in the polymeric coupler molecule presents a problem. That is, it is necessary to resort to a solvent other thanaqueous alkali for incorporating the polymeric color formers into emulsion layers. Not only must a solvent be selected which satisfactorily dissolves the polymeric color former and dye images obtained therefrom but other requirements must be met. Since the polymeric color formers of the invention have limited solubility in hydrophilic organic colloid emulsion layers-such as gelatin emulsion layers, the color formers must be dispersed in the emulsion layer in a form which will prevent them from separating from the emulsion as'agglomerates of polymeric coupler.

We have found that if polymeric color formers, especially the hereinafter described polymeric color formers, are first dissolved in a particular group of comparatively high. boiling crystalloidal solvents which have. a high solvent action for the dye formed from the colo r'former, and the resulting solution of polmeric color former is then dispersed in an emulsion layer as finely divided liquid particles, the polymeric color former is prevented from separatingout from the emulsion either during coating or storage. of .the emulsion or during processing of the emulsion and subsequent storage. of the processed emulsion. When polymeric color formers are put into emulsions in this manner, the color formers are non-diffusing in the emulsion layer as manifested by the high definition of the dye images prepared from the emulsions. To our knowledge polymeric color formers have not previously been incorporated into emulsions by means of the high boiling crystalloidal solvents.

It is therefore one object of our invention to provide polymeric color formers of particular use with certain crystalloidal solvents. Other objects include providing emulsions containing dispersions of the polymeric color former which emulsions are adapted to forming dye images in conventional processes of color photography. Another object is to provide representative methods for using the emulsions of the invention in preparing colored photographic reproductions. Other objects will appear from the'followin'gdescription'of our invention;

Theaccompanying drawings illustrate in greatly ens larged cross-sectional view the appearance of a typical photographic element contemplated by our invention.

Thepolymeric color formers with which ourinvention is particularly concerned contain recurring polymeric units freeof alkali solubilizinggroups, such as sulfonic acid and carboxylic acid groups, having the following general structure:

where A represents either a carbonyl or sulfonyl group and R represents a group of atomscontaining an organic radical such as a pyrazolone group, a naphthol group or a benzoylmethylene group which is capable of reaction with the oxidation product of the primary aromatic amino developing agents'toform' a dye. As will be ap parent, the polymeric couplers include film-forming polymers having the generalstructures the value of" the integer n being afun'ction' of molecular weight or degree of polymerization of thepolymer and Ris as above noted. V

The polymeric couplers having the'above' structures are acylation products of polyaminostyrene with acidhalide's or esters of color formers. The preferred polymeric couplers having the above. structures are liomopolym'er's in'that' they contain substantially no' amino'st' re'ne units which have not been acyla'ted by the acid halide or'ester color former. However, useful polymeric color formers having the above structures can be selected from those acylated polyaminostyrenes-which contain a minor. proportion of aminostyrene units which have not been acylated.

Examples of polymeric coupler compounds havingthe above structures and contemplated by our invention are as follows:

NH-CO The crystalloidal materials which are used for dispersing such polymeric coupler compounds in hydrophilic photographic emulsion layers are water-insoluble, organic, crystalloidal materials having boiling points above about 175 C. The crystalloidal materials have a high solvent action for the polymeric color formers as well as for the dye images formed therefrom.

The high boiling crystalloidal materials are generally liquid at ordinary temperatures or low melting solids (below 100 C.). It has been found also that in general the most useful compounds contain one or more polar groups such as halogen, hydroxyl, carboxylic acid, amide, ketone, etc., although this is not a limiting factor. They should have a highsolvent action for the coupler and for the dye produced by coupling and should, of course, be inert toward the silver halide emulsion in which they are incorporated. They should also be substantially colorless and stable toward light, heat and moisture, in addition to being inert to the various processing baths which may be encountered such as developers, oxidized developers, silver removal baths and fixing baths. They should be of low volatility and in general we have found that compounds suitable for this purpose have boiling points above 150 or 175' C. at atmospheric pressure. They should have a sufficiently low refractive index so that the solutions of couplers in them have approximately the same'refractive index as gelatin, thereby minimizing the opacity or light scattering of the coating. Most couplers themselves have high refractive indices and for this reason it is desirable that the oil formers have low refractive indices. They should be easily dispersible in emulsions and should be chemically inert toward the couplers and dyes formed from them.

Examples of the crystalloidal materials useful in our invention are N,N-diethylcapra'mide, di-n-butylphthalate, N-n-amylphthalimide, tetrahydrofurfuryl benzoate, triphenylphosphate, n-butyl sulfone, ethyl-N,N-di-n-butylcarbamate, ethyl-N-phenylcarbamate, tetrabydrofurfuryl succinate, ethyl benzyl malonate, methyl phthalate, nbutyl phthalate, n-amyl phthalate, fi-methoxyethyl phthalate, fi-ethoxyethyl phthalate, B-butoxyethyl phthalate, butyl o-methoxybenzoate, n-hexyl benzoate, benzophenone, p-sec-amylbenzophenone, tricresyl phosphate, diphenyl mono-p-tert. butyl phenyl phosphate, monophenyl di-o-chlorophenyl phosphate, tri-o-phenylphenyl phosphate, p-toluenesulfonyl methyl-o-toluidine, p-toluenesulfonyl dimethylamide, p,p'-di-n-amylbenzenesulfonamide, p-toluenesulfonyl di-n-butyl amide, N,N-diethyl-N,N'- diphenyl urea, N,N-di-n-butyl urea, etc., as well as the other crystalloidal materials disclosed in the Jelley and Vittum U. S. Patent 2,322,027 and in the Mannes and Godowsky U. S. Patents 2,304,939 and 2,304,940, as well as the alkyl amides disclosed in the Sawdey and Vittum U. S. Patent 2,533,514.

Example I.-Yellow polymeric color former Coupler No. 1 having the structure shown above was prepared as follows:

In an all-glass reflux apparatus equipped with a mechanical stirrer and a reflux condenser, 4 g. of polyaminostyrene (U. S. 2,274,551) were dispersed with stirring in 40 cc. of dry pyridine. To the dope obtained were added 11.5 g. of p-benzoylacetaminobenzenesulfonyl chloride and the reaction was heated with stirring for 1 hour on a steam bath. It was then diluted with 40 cc. of pyridine, filtered through a plug of glass wool and poured into 600 cc. of distilled water. The friable precipitate obtained was washed with distilled water and then stirred for 30 minutes with 500 cc. of a 4:1 mixture of water and pyridine. The product was then washed with distilled water and dried in vacuum. The dried product was stirred with 500 cc. of ether and again dried in vacuum. The polymer coupler was soluble, for example, in N,N-diethyl capramide. Yield 9.5 g.

One gram of the polymeric color former prepared above was dissolved by heating in 6 cc. of diethyl capramide. The solution obtained was then milled at 40 C. into 22 cc. of a 10 percent gelatin solution containing 0.20 gram of a wetting agent. The resultant dispersion was then mixed with 50 cc. of a warm (40 C.) aqueous gelatin silver halide emulsion containing approximately 2.5 percent silver halide calculated as silver and 7 percent gelatin. This warm (40 C.) mixture was then made up to a volume of cc. with water and coated on a film base, about 8 cc. of emulsion being utilized per square foot of coating surface. The film at this stage would appear substantially as shown in the accompanying drawings wherein layer 10 of the film represents the film base and layer 11 the emulsion layer containing the finely divided liquid particles of the polymeric coupler compound 12.

The dried coating was then exposed under a subject and developed in a color developing solution such as the following:

2-amino-5-diethylaminotoluene hydrochloride 2 Sodium sulfite 2 Sodium carbonate 20 Potassium bromide 2 Water to 1000 cc.

Following development, the silver image in the exposed area of the emulsion layer was bleached to silver halide in a well-known manner and the silver halide in the emulsion layer all fixed out in a conventional fixing solution. The dye image remaining in the emulsion layer was yellow, had good density and contrast. Examination of the dye image indicated that the diffusion of the polymeric coupler and dye image therefrom in the emulsion layer was negligible. a

Example :I-l. -.Cyan polymeric color former Coupler No. 2 shown above was'prepared as "follows: Three grams of polyaminostyrene were dispersed in 30 cc. of dry pyridine with stirring. Fourteen grams of l-hydroxy-Lchloro-N-B- 3-chlorosulfonylbenzamido ethyI-Z-naphthamide were added and the reaction was heated for 2 hours with stirring on a steam bath. The dope obtained was diluted with 30 cc. of pyridine, filtered through a plug of glasswool and poured in a mixture of -.4 0,0 cc. of distilled water and 100 cc. of pyridine with stirring. The precipitate was filtered, washed with water,

and thenstirred for 30minutes-with .500 cc. of 4:1 water and pyridine.

The product was then filtered -on to a Buchnenfunnel, and washed on the funnel with water followed by several chang s :of absolute ethyl alcohol.

The solid was driedjnza vacuum desiccator over calcium chloride under a cdnstantlyapplied water pump vacuum.

Y;ie,ld 95 g. Theresincoupler was soluble, for'example, in .tricresylphosphate.

,A silver halide emulsion containingthe polymeric coupler-was prepared by dissolving the coupler in dibutyl phthalate in the ratio of 1 part ofcoupler to 12 parts of the solvent. In the manner of the above example, the solution of polymeric coupler was milled into an aqueous gelatin solution containing a dispersing agent and the resultant dispersion mixed with a gelatino-silver halide emulsion. After coating the emulsion upon a film base, it was exposed and color developed as in the above example to obtain a cyan image of good density and contrast. Examination of the image indicated that the polymeric coupler from which it was derived had the desirable characteristic of low diffusion in the emulsion layer.

Example III.'Ye llow polymeric coupler Coupler No. 3 shown above was prepared as follows:

Two g. of polyaminostyrene were suspended in 50 cc. of ethyl benzoylacetate in a flask equipped with a mechanical stirrer, andlthe reaction mixture with stirring was heated in an oil bath. The temperature of the oil bath' was slowly raised. At about 120 C. .the polymer dissolved. The reaction was maintained at 170-175 C.

'for one. hour. The solution was filtered through aplug pared above was dissolvedin di-n-butyl phthalate (6 'g.)

;by heating to 170 with stirring. After cooling some- -what, the viscous solution was mixed with 22 ml. of

gelatin containing 0.20 g. of Alkanol B (an alkylnaphthalene sodium sulfate) and dispersed by milling. This dispersion'was mixed with 50 ml. of a'standard unsensitized emulsion containing approximately 2.5% silver and 7% gelatin. This mixture was made up to a volume of 90 ml. with water and coated at approximately 8 rnl./ft. The dried coating when processed in Example I gave a yellow dye image of suitable contrast and density. The amount of difiusion of this color former in a photographic layer was negligible, making it possible to use it in a multilayer system without-encountering any difficulty from so-called interimage effects.

Example I V.-Cyan polymeric coupler Coupler No. 4 above was prepared as follows:

Four grams of polyaminost-yre'ne were dispersed in 40 cc. of dirnethyl formamide. To the dope was added g. of phenyl l-hydrbxy-Z-naphthoate, and the reaction washeatedwith stirring in an oil-bath'at 180 Csfor 1 hour. The-.dopewas filtered through a-plug of glasswool, cooled andpoured into 500 cc. of absolute ethyl alcohol. The finely divided tan precipitate was filtered onto a Buchner funnel, washed with ethyl alcohol and then stirred in a beaker with two 500 cc. portions of ;fr,esh ethyl alcohol,,-filtering aftercac-h. The product was dried in avacuum desiccator-overcalciumchloride .undera constantly applied water pump vacuum. The yield was 9.8 g. The product was soluble, for example, in vhot dibutyl phthalate or hot tricresyl phosphate and the solutions could be cooled'without precipitation.

An emulsion was prepared containing the cyan coupler No. 4 prepared as above ;by dissolving the coupler in dibutyl phthalate ,in the ratio of 1:12 followed by :milling the solution of coupler in a gelatinsolution and mixing the resultant dispersion ;-in a -silver "halide emulsion. A coating of the emulsionprocessed as described in the above examples yielded acyan'image of good density and contrast, very little diffusion being apparent in the coatmg.

In the manner of the above examples the aminostyrene polymer can-be reacted with '5-pyrazolones,-e. g,, S-pyrazolone sulfonyl or carbonyl halides to obtain polymeric couplers which can ,beincorporated into photographicemulsions by :meansof the coupler solvents in the manner described above.

.Examp'le V -A'twola'yer color film was prepared -by first dissolving the polymeric coupler of Example-IV indibutyl phthalate and mixing the resultant isolution' w i-th a red-sensitive gelatino-silver halide emulsion. This emulsionwas then coated onto a film base. Followinglthis, the'red-sensitive emulsion layer was overcoated with a thin gelatin layer. A solution of the polymeric coupler of Example 111 in dibutyl phthalate was prepared and this was dispersed in'a blue-sensitive gelatino silver halide emulsion. Following coating of the resultant emulsion upon the thin gelatin layer, the film was exposed toa :colored :subject and processed as described in the above examples to yield a cyan image in the regions of red exposure and yellow images in the regions of .blue exposure. Examination of the cyan and yellow images indicated that very good color separation had been obtained. I

Results comparable to those ofthe above example are obtained with emulsions containing dispersions of the other polymeric couplers of the invention; for '6XHI11P165'8. pyrazolone polymeric coupler yields a magenta dye image upon color development and an emulsion containing a dispersion of this coupler may be employed with the cyan and yellow emulsions above described in i3. multilayer color film designed for the production of subtractively colored reproductions.

The above polymeric color formers are 'by 'no means exhaustive of those contemplated by our invention. The

aminostyrene homopolymercan be partially or fcompletely acylated with other coupler molecules containing reactive acid halide'or ester groups such' as those sulfonyl halide couplers disclosed by the Weissberger and Salminen U. S. Patent 2,484,477, Examples I to IV, and those acid halides used in the preparation of compounds 1 to 21 of said patent'as well :as the acid halide couplers of French Patent 980,390 (U. S. patent abstr. 774,890 published April 24, 1951). Other coupler molecules'containing acid halide .or ester groups which can be reacted with the aminostyrene polymer to obtain polymeric couplers will occur to those skilled in thewart.

As will be apparent from the above examples, the polymeric couplers which are solids under ordinary .con-

ditions are converted into liquids of oil consistency by use of the crystalloidal materials which are insoluble or only slightly soluble in water and in the liquid photographic emulsion. Accordingly, there islittle tendency for the couplers to precipitate in the emulsion even when present infairly high'concentrations. While itis desirable 7 that the oil solutions of the color formers be liquid at the usual emulsion melting temperatures (about 40 C.), to facilitate dispersion in the emulsion, if the dispersions of the polymer solutions in the emulsion gel after coating this has no harmful efiect on their use. The invention, therefore, includes a sensitive photographic silver halide emulsion having a water-soluble binder such as' gelatin in which are dispersed particles composed of coupler and a high-boiling water-insoluble crystalloidal organic compound. ln carrying out the invention, the coupler which has been mixed with the high-boiling organic compound to produce an oil-like mixture may be dispersed in water or gelatin solution or in any aqueous binder of colloidal character which is miscible with the silver halide emulsion. The dispersion may be effected with the aid of homogenizer, colloid mill or the like and the dispersions may be stabilized by the addition of emulsifying agents such as those of the well known higher fatty alcohol sulfate type. The dispersion may also be formed by dispersing a solution of coupler, and crystalloidal material, in a solvent of low boiling point such as butyl acetate, with water or gelatin solution and subsequently removing the low boiling solvent by evaporation. Here also an emulsifying agent may be used.

In our process we prefer to use the customary gelatinosilver halide emulsions although other water-soluble colloidal materials can be used for the photographic emulsion such as agar or water-soluble synthetic resins. The emulsions may be used in single layer or in multilayer coatings and our invention is especially designed for the production of multilayer coatings for natural color photography.

It is sometimes advantageous to employ a mixture of two or more individual crystalloidal materials or oil formers in the same dispersion in order'to obtain the desired combination of properties. Thus one might use a mixture of one compound having exceptionally good solvent action, with another compound added in the correct proportions to give the final dispersion the desired refractive index.

We have referred to dissolving the coupler and the high boiling solvent in low boiling solvent and dispersing the mixture in an aqueous solution after which the lower boiling solvent is removed. Although this is not necessary in our process, in many cases it is desirable to proceed in this way using a solvent which can be removed before coating the emulsion. Low boiling solvents suitable for our purposes include nitromethane, nitroethane, methyl, ethyl, propyl and butyl acetates and ethyl and butyl formates.

In dispersing the mixture of coupler and high boiling solvent in the aqueous solvent, it is desirable to use an emulsifying agent such as sodium lauryl sulfate, or Arctic Syntex T (U. S. Patent 1,932,180). Gelatin may also be used as an emulsifying agent or the mixture of coupler and high boiling solvent may be dispersed directly in the photographic emulsions.

The above polymeric couplers are to be distinguished from similar alkali-soluble couplers made from a polyaminostyrene-maleic acid copolymer. That is, the polymeric couplers made by reaction of an aminostyrenemaleic acid copolymer with either p-benzoylacetaminobenz'ene sulfouyl chloride or m-3,5'-dichloro-2'-hydroxy-4'- methyl carbarnyl benzenesulfonyl chloride, can be incorporated into emulsions from aqueous alkaline solution. These couplers are less preferred in the present crystalloidal solvent emulsion system because of the presence of the carboxyl groups which tend to make the couplers more diffusible in the development step.

What we claim is:

l. A gelatino-silver halide emulsion having dispersed therein finely divided particles of a mixture of asubstantially water-insoluble, organic, crystalloidal material having a boiling point above about 175 C., and a film- -forming polymeric color former freeof carboxyl and sulfo 8 groups and containing recurring units having the following general structure:

wherein A represents a member of the group consisting of carbonyl and sulfonyl groups, and R represents a group of atoms containing an organic radical capable of reacting with the oxidation product of a primary aromatic amino developing agent to form a dye, said crystalloid-al material having a high solvent action for the color former and the dye formed therefrom.

2. A gelatino-silver halide emulsion having dispersed therein finely divided particles of a mixture of a substantially water-insoluble, organic, crystalloidal material having a boiling point above about C., and a filmforming polymeric color former free of carboxyl and sulfo groups and containing recurring units having the following general structure:

sulfo groups and containing recurring units having the structure:

OH:rC H- wherein R represents a group of atoms containing an organic radical capable of reacting with the oxidation product of a primary aromatic amino developing agent to form a dye, said crystalloidal material having a high solvent action for the color former and the dye formed therefrom.

4. The emulsion of claim 2 wherein R of the designated color former represents a group of atoms containing a phenolic hydroxyl group capable of reacting with the oxidation product of a primary aromatic amino develop ing agent to form a dye.

5. The emulsion of claim 2 wherein R of the designated color former represents a group of atoms containing a methylene group capable of reacting with the oxidation product of a primary aromatic amino developing agent to form a dye. w

6. The emulsion of :claim 3 wherein R of the designated color former represents a group of atoms containing a methylene group capable of reacting with the oxidation product of a primary aromatic amino developing agent to form a dye.

7. The emulsion of claim 3 wherein R of thedesi gnated color former represents a group of atoms containsaid crystalloidal material having a high solvent action for the color former and the dye formed therefrom.

9. A gelatino-silver halide emulsion having dispersed therein finely divided particles of a mixture of a substantially water-insoluble, organic, crystalloidal material having a boiling point above about 175 C., and a film-forming polymeric color former free of carboxyl and sulfo groups and containing recurring units having the following structure:

said crystalloidal material having a high solvent action for the color former and the dye formed therefrom.

10. A gelatino-silver halide emulsion having dispersed therein finely divided particles of a mixture of a substan- 10 tially water-insoluble, organic, crystalloidal material having a boiling point above about C., and a film-forming polymeric color former free of carboxyl and sulfo groups and containing recurring units having the following structure:

NH-SOzO-NHOOCHzCO-O said crystalloidal material having a high solvent action for the color former and the dye formed therefrom.

11. A gelatino-silver halide emulsion having dispersed therein finely divided particles of a mixture of a substantially water-insoluble, organic, crystalloidal material having a boiling point above about 175 C., and a film-forming polymeric color former free of carboxyl and sulfo groups and containing recurring units having the following structure:

-OHZCH' GONHwHmNHOO said crystalloidal material having a high solvent action for the color former and the dye formed therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 2,322,006 Fierke et a1. June 15, 1943 2,322,027 Jelley et al. June 15, 1943 2,533,514 Sawdey et a1 Dec. 12, 1950 2,759,816 Minsk Aug. 21, 1956 

1. A GELATION-SILVER HALIDE EMULSION HAVING DISPERSED THEREIN FINELY DIVIDED PARTICLES OF A MIXTURE OF A SUBSTANTIALLY WATER-INSOLUBLE, ORGANIC, CRYSTALLOIDAL MATERIAL HAVING A BOILING POINT ABOVE ABOUT 175*C., AND A FILMFORMING POLYMERIC COLOR FORMER FREE OF CARBOXYL AND SULFO GROUPS AND CONTAINING RECURRING UNITS HAVING THE FOLLOWING GENERAL STRUCTURE: 